Use metal dust for minerals in the soil?

[mountaindweller]

Phil Nauta writes in his book "building soils naturally" that you can use quarry material to increase the mineral content of your soil and you can do that without a soil test.
The local landscape supply sells metal dust which they call black metal dust, but they don't know anything about it.
Is this the right thing?
I guess there's something missing in the soil because there are some crops which don't grow properly: broccoli (important, kohlrabi (can do without it)and beetroots don't grow crazy either.

[raymondo]

Doesn't sound like the right thing. Rock dust, from a quarry for example, is simply crushed rock. Metal dust sounds like something from a foundry. I use crusher dust from time to time in the garden but I had a pile left over from making a water tank pad. You can buy rock dust for gardens but it's quite expensive. Crusher dust is much cheaper. The difference of course is that one has a list of ingredients whereas the other doesn't. Try your local rural supplies store for minerals. Alroc is a brand often found in rural supply stores.

[trixtrax]

Don't use any metal dust - it will poison your soil. Not all rocks are created equally. Some are near useless in terms of providing minerals, others can have too high of a concentration of a mineral, ie some granite are extremely high in aluminium while others are safe to use.

Create and use compost. Use biodynamic accumulator plants and mulch plants. Check out keyline design. Weed species and the prevalence/state of said weeds can be read to figure soil conditions and general mineral availability. Seaweed meal, azomite, bone meal, granite dust are great for micro-nutrients but can be over-applied or not appropriate for certain situations. The same goes for any mineral amendment. But, definitely spend a few bucks to get a accurate soil test to see what mineral profile you have for your different soils then that way you will be able to figure exactly what NPK but also more importantly which micro-nutrients you are missing. Look for tests that show calcium, magnesium, zinc, sulfur, lead, copper, arsenic, etc and any other mineral readings. Also pH and cation exchange. Other figures are a bonus. From there you can add exactly what is missing. Guessing is dangerous and can at very least wreck your soil/have no significant effect to at worst poison you and your loved ones. Plus, since we are growing food it ought to be damn mineral rich with a full bevy of the nutrients of planet Earth.

This said are you noticing any yellow leaves or yellowing along veins, contortion of the leaves, or anything otherwise odd? Also, what else do you grow? What grows well and what else does poorly? Are other Brassicas, like kale/collards growing normal/slow for your area? How do onions, in particular, bulbing onions grow for you? What about other root/tuber crops, like potatoes?

[richardw]

Thanks for the warming on granite dust Chris, i wont use any more.

[MikeH]

Jul 19, 2014 1:35:36 GMT -5 trixtrax said:

Seaweed meal, azomite, bone meal, granite dust are great for micro-nutrients but can be over-applied or not appropriate for certain situations. The same goes for any mineral amendment.

Focusing just on azomite and granite dust, what situations would they not be appropriate for?

But, definitely spend a few bucks to get a accurate soil test to see what mineral profile you have for your different soils then that way you will be able to figure exactly what NPK but also more importantly which micro-nutrients you are missing. Look for tests that show calcium, magnesium, zinc, sulfur, lead, copper, arsenic, etc and any other mineral readings. Also pH and cation exchange. Other figures are a bonus. From there you can add exactly what is missing.

Conventional soil tests only test for soluble minerals not for those in insoluble form in the soil. If you can find a total soil test, you'll have a better idea of the condition of your soil.

Agronomic soil tests generally have been developed to try and extract the plant available fraction of a nutrient, or at least, a fraction that is strongly correlated to the plant available fraction. There has been less interest in the total levels of nutrients in the soil from an agronomic viewpoint, as they are often poorly correlated with plant availability.  There's also this article on Soil: The need for Total Testing.

Making the insoluble minerals available requires a healthy microbiology in your soil. From Nutrient uptake in mycorrhizal symbiosis,

Mycorrhizal infection may affect the mineral nutrition of the host plant directly by enhancing plant growth through nutrient acquisition by the fungus, or indirectly by modifying transpiration rates and the composition of rhizosphere microflora.
A capacity for the external hyphae to take up and deliver nutrients to the plant has been demonstrated for the following nutrients and mycorrhizas; P (VAM, EM, ECM), NH4 + (VAM, EM, ECM), NO3 - (ECM), K (VAM, ECM), Ca (VAM, EM), SO4 2- (VAM), Cu (VAM), Zn (VAM) and Fe (EM). In experimental chambers, the external hyphae of VAM can deliver up to 80% of plant P, 25% of plant N, 10% of plant K, 25% of plant Zn and 60% of plant Cu.

Page 143 of this article - web.archive.org/web/20111026071300/http://eprints.nwisrl.ars.usda.gov/818/1/1076.pdf, says the same thing.  Getting a healthy microbiology in your soil includes no till or minimal till since tilling destroys the mycorrhizal network.  It also includes building soil tilth by increasing soil organic matter.  Mycorrhizal fungi need SOM to thrive.
 

[trixtrax]

richardw I'd test it if you can to see where you stand on Aluminum content.

Thanks for the information MikeH, absolutely agree with your points about microflora/mycorrhizal networks/OM.

Speaking of the Azomite, if K or Aluminium was already high I would shy away it maybe apply a seaweed meal low in K to try to meet micro-nutrient needs (which it is here). Granite dust I'd skip if the soil was high in Aluminium. Otherwise, they are great remineralizers.

My thought on a soil test, conventional or more accurate test like you describe (enjoying the article), it's a case of knowing roughly where a soil stands. I like to apply a fraction of what is needed over time, watch and observe, repeat or modify, and so on.

---

I should have said also look for a test that includes Boron, which is deficient in many places, easy to apply but also easy to overapply so watch out. Boron deficiency causes all sorts of wonky problems like one possible cause of catfacing in strawberrie or weird rotting in lettuce

[mountaindweller]

Thanks for the information! I have to look up on azomite (don't know what it is) and I use seasol, but today I saw something called "seamungus" at the local produce store, the price was quite impressive though.
I use a lot of wood mulch on the pathways with a lot of cardboard underneath and this is good for the funghi (I would be great if I could identify them maybe there are even edible ones!. And I like comfrey and borage as mulch.
What Aussie soil labs do you use?

[MikeH]

Jul 21, 2014 1:04:53 GMT -5 trixtrax said:

Speaking of the Azomite, if K or Aluminium was already high I would shy away it maybe apply a seaweed meal low in K to try to meet micro-nutrient needs (which it is here). Granite dust I'd skip if the soil was high in Aluminium. Otherwise, they are great remineralizers.

pH is a big factor. The soil pH is probably the single most important management factor controlling the amount of Al+++ in the soil solution. Soluble Al is present in the soil when the pH begins to drop below pH 6.0. However, it is inconsequential in the vast majority of soils until the pH drops below pH 5.5. Even then, it is rarely a problem until the soil pH drops below pH 5.0. However, the amount of soluble Al increases dramatically in nearly all soils as the soil pH drops below pH 5.0. In these extremely acid soils, only those species adapted to acid soils (such as blueberries, cranberries, and acid-loving ornamentals) or the few crop species bred to tolerate high soil Al levels can be expected to do well.

[trixtrax]

pH is the primary governing factor of heavy metal availability, yes agreed, but my thought is if Al is already testing high I'm going to try my best to apply a minimal amount down if possible. As long as the soil stays alkaline Al is not a problem, but if there comes a time where it tends acidic, Al will become a problem. Maybe someone else moves there and doesn't know/care to apply lime, or maybe its a SHTF scenario...

[MikeH]

Jul 22, 2014 1:25:12 GMT -5 trixtrax said:

pH is the primary governing factor of heavy metal availability, yes agreed, but my thought is if Al is already testing high I'm going to try my best to apply a minimal amount down if possible. As long as the soil stays alkaline Al is not a problem, but if there comes a time where it tends acidic, Al will become a problem. Maybe someone else moves there and doesn't know/care to apply lime, or maybe its a SHTF scenario...

Absolutely. Al may not be a problem because of pH but unless some is aware of the pH/Al relationship, Al could become a problem. As you say. best to reduce the problem even if it is only a potential problem.

This - web.archive.org/web/20140722144706/http://www.hill-laboratories.com/file/fileid/15530 - is a pretty good summary of soil test interpretations, ie, how soil chemistry fits together.

[mountaindweller]

I guess I have to search an Aussie soil lab - any recommendations?

[trixtrax]

sometimes universities have testing services

[trixtrax]

MikeH, I want to clarify I am definitely pro-azomite. Also, found out about this product at a trade show last winter which is supposedly similar in mineral profile to azomite and local to us as it's out of Oregon, but haven't experimented with it yet: cascademineralsnw.com/product_facts.html

[MikeH]

Jul 23, 2014 0:06:46 GMT -5 trixtrax said:

MikeH, I want to clarify I am definitely pro-azomite. Also, found out about this product at a trade show last winter which is supposedly similar in mineral profile to azomite and local to us as it's out of Oregon, but haven't experimented with it yet: cascademineralsnw.com/product_facts.html

We've been using this - www.borealagrominerals.com/ this year on all our vegetable, fruit, nut, and berry plantings. We've also been applying mycorrhizal fungi granular powder to the roots of all our plantings as well.  And we've been using a soluble product for old plantings that were never inoculated. We're applying the Spanish River Carbonatite because we don't know how long it will take the mycorrhizal fungi to begin providing macro and micro nutrients to the plants. The SRC is cheap and easy to apply so we'll probably use it for a couple of more years.  Hopefully, by that time our soil will have a well establish mycorrhizal fungi network.

[raymondo]

Mountaindweller, the Environmental Analysis Laboratory at Southern Cross University in Lismore in northern NSW has a pretty good reputation.